Antenna feeder drive



Aug. 26, 1958 R. EVANS ANTENNA FEEDER DRIVE 3 Sheets-Sheet 1 Filed April26, 1956 INVEN TOR. LAWRENCE E. EVANS mmw ATTORNEYS Afig. 26, 1958 R.EVANS 2,848, 05

ANTENNA FEEDER DRIVE I Filed April 26, 1956 3 Sheets-Sheet 2 1 1 64-INVENTOR.

LAWRENCE E. EVANS ,1 QO/QM ATTORNEYS Aug. 26, 1958 R. EVANS 2,848,905

ANTENNA FEEDER DRIVE Filed April 26, 1956 5 Sheets-Sheet 3 FIG. 5

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FIG. 6

IN VENTOR LAWRENCE R. E VA/VS %&@ 31/? W ATTORNEYW United States PatentANTENNA FEEDER DRIVE Lawrence R. Evans, Washington, D. C., assignor tothe United States of America as represented by the Secretary of the NavyApplication April 26, 1956, Serial No. 580,973

Claims. (Cl. 74--660) (Granted under Title 35, U. S. Code (1952), sec.266) The in'vention described herein may be manufactured and used by orfor the Government of the United States of America for governmentalpurposes without the payment of any royaltiesthereonor therefor.

T he present invention relates to an antenna feeder drive and moreparticularly to an antenna feeder or horn drive that permits a changefrom spiral scanning'to conical scaning in a short period of time.

Heretofore the shifting or changing of antenna feeder drives from oneform of scanning to another form has been accomplished by highly complexdevices that were necessitated by high speed shifting and these complexdevices were difficult, if not impossible,-to balance dynamically.Consequently often mechanically unsound mechanisms were employed todo'the shifting and itwas not uncommon to have aniodeldisintegrate' dueto faulty balancing.

The present invention providesa novel way of driving a feed antenna orantennafhorn'in' which a fir'st'gear train arrangement drives a sun gearat a fixed speed and a second gear train arrangement is equipped-todrive a planet gear at two different speeds, one of which is the same asthe speed of the sun gear. When the sun gear and the planet gear aretraveling at the same speed, there is no relative motion between themand the antennafeed horn, which is connected to the sun gear, is rotatedin'a conical pattern. W'h'enthe sun gear and the planet-gear arerotating at different speeds, there is relative motion between oneanother and the planet gear will rotate around the sun gear withacha'r'acteristic planetary motion. This planetary motion will causetheantenna feed horn to be rotated in a spiral pattern, whichis' desirablefor search purposes.

It is therefore a general object of the present invention to provide anovel means ofdrivingan antenna feed horn whereby the feed horn can bemade tomutate either in a conical'or spiral pattern.

Another object is to provide for shifting from conical rotation tospiral rotation'in a short'p'eriod'of time.

Other objects and many of: the attendant-advantages of this inventionwill be readily appreciated as the same becomes better understood byreference to the following detailed description when considered inconnection with the accompanying drawings wherein:

Figure 1 is a gear schematic showing the complete invention;-

Figure 2 is a partial sectional view showing a-clutching arrangement;

Figure 3 is a diagrammatic view showing a spiralpattern that the antennafeed horn can traverse;

Figure 4 is a partial sectional view showing avariation in a clutchingarrangement;

Fig. 5 is a fragmentary diagrammatic view with parts thereof broken awayand in section and showing with greater particularity the details of thepivotal connection between certain parts of the structure illustrateddiagrammatically in Fig. 1; and

Fig. 6 is a diagrammatic view of the gimbal type 2,848,905 Patented Aug.26,1958

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ure 1 a drive motor 11 having a gear 12 attached to shaft 13. Gear 14 isattached to shaft 15, which is connected to carrier plate 16 and carrierplate 16' is rotated at the same speed as shaft 15. A shifting mechanismhas a first clutch plate 17 that has a gear portion 18 that meshes withgear 14. Gear 19 which is also attached to shaft 15 meshes with gearportion 21 which is integral with a second clutch plate 22.

Referring now to Figure 2 of' the drawings, it can be seen that the two.clutch plates 17 and 22 are rotatably mounted on clutch shaft 23 bymeans of bearings 24. A slidable clutch plate 25 is keyed to clutch 23by means of a key 26 which engages keyway 27. The slidable clutch plate25 has a collar 28 that extends outwardly and a shaft 29 of a solenoid31 is attached thereto. Clutch plate 25 is free to rotate within collar28, but any lateral movement of collar 28 is transferred to clutch plate25 through pins 40.

As shown in Figure 2, solenoid 31 could be of the pushpull type, and theslidable clutch plate can be moved forward or backward to engage thedesired clutch plate. As illustrated in Figure 40f the drawings,solenoid-31 might-be a single action type and when not energized, spring30'will keep the slidable clutch plate 25 engaged with clutch plate 22.

Referring again to Figure 2 of the drawings, it can be seen thatslidable clutch plate 25 has a plurality of teeth 32 that mesh withteeth on the face of clutch plate 22. The slidable clutch plate 25' hasa single'tooth 33cm the other end, and this single tooth 33 can beengaged with a notch34 which is provided on the face of first clutchplate 17 It can thus be seen that since'the slidable clutch plate 25 canonly be engaged in a single position, which is when tooth 33 is in notch34, then whenever slidable clutch plate 25 is engaged with first clutchplate 17, there will always be the same angular relationship betweenclutch shaft 23 and shaft 15. The need for this same angularrelationship will be understood when the operation of the device isdescribed.

Referring again to Figure 1 of the drawings, it is shown that gear'35 isattached to clutch shaft 23 and meshes with gear 36 which is part ofsleeve 37. Sleeve 37 is rotatably mounted on shaft 15 by means ofbearings 38. Shaft 39, which is rotatably mounted through carrier plate16, has gears 41 and 42 attached thereto, gear 41 being driven by gear43 which is part of sleeve 37. Pri mary gear 42 is on the same shaft asgear 41 and is in mesh with secondary gear 44. Gear 41 serves as anorbital gear with respect to gear 43, and primary gear 42, being carriedby 39, partakes of the same orbital motion as 41, however, only withrespect'to shaft 15. Shaft 39 is'capable either of turning or notturning. When shaft 3% is turning, primary gear 42 drives secondarygear-44 about its shaft 45 which is connected tocarrier I6, carrying theeccentric 49 and the counterweight Sit foreccentric 49 with-it.

Referring still to Figure 1 of the drawings,-it can be seen thatsecondary gear 44 is rotatably mounted on shaft 45 by means of a bearing46; Antenna feed born 47 is connected to wave guide 52 and pivotallycoupled me chanicall'y at 49 as by a ball and socket coupling at'51 Fig.5 to the second gear 44 and mounted in gimbalassembly 48 Figs. 1 and 6.Y I

In operation, shaft 15 is driven at: a fixedsp'eed b drive motor 11. Byway of example, the speed of shaft 15 might be 1750 R. P. M. Gears 14,18, 35, and 36 have the same number of teeth and it can be seen thenthat whenever slida'ble clutch plate 25 is engaged with first clutchplate 17, clutch shaft 23 will be turning at the same speed as shaft 15,and likewise sleeve 37 will be rotating at the same speed as shaft 15.When shaft 15 and sleeve 37 are turning at the same speed, there will beno relative motion between gears 41 and 43 since carrier plate 16 isinrotation with shaft 15. Also, there will not be any relative motionbetween primary gear 42 and secondary gear 44.

Referring to Figures 1 and 3 of the drawings, it can be seen that thenutatiou of the antenna feed horn 47 in a conical pattern is caused bythe offset of the coupling 49 from the centerline of shaft 15 and thatwhenever shaft 15 is rotating, the centerline of coupling 49 is rotatingin a circle a, as shown in Figure 3. Since the antenna feed horn 47 issupported in gimbal assembly 48, the movement of the coupled end of theantenna feed born 47 will cause it to nutate in a conical pattern.

When it is desired to change from a conical scanning pattern to a spiralscanning pattern, the clutch assembly is shifted so that the slidableclutch plate 25 is engaged with the second clutch plate 22. Clutch shaft23 will then be turning at a speed different from the speed of shaft 15due to the gear ratio of gears 19 and 21 and consequently sleeve 37 willbe turning at a speed different from the speed of shaft 15. The speeddifference, by way of example, may be on the order of 120 R. P. M. andthe speed of the sleeve 37 might be either faster or slower thanthespeed of shaft 15. It can be seen that when secondary gear 44 isrotating there will 'be relative motion between secondary gear 44 andcarrier plate 16 and consequently the antenna feed horn will nutate in aspiral pattern c, as shown in Figure 3 of the drawings.

Referring again to Figure 3 of the drawings, it can be seen that if thespeed difference between sleeve 37 and shaft 15 is, for example, 120 R.P. M., then the center of coupling 49 will travel from circle a to pointb and back again to circle a in one half second, along the path shown byspiral 0. Also the relative motion between first clutch plate 17 andslidable clutch plate 25 is 120 R. P. M. or 2 revolutions per second,and if it is desired to change from spiral scanning to conical scanning,solenoid 31 can be energized which will move slidable clutch plate 25toward first clutch plate 17. Tooth 33 will then slide around the faceof first clutch plate 17 by the driving force of teeth 32 still inpartial engagement until notch 34 is 'in alignment with tooth 33, andtooth 33 will then engage notch 34 and lock the slidable clutch plate 25and first clutch plate 17 together, thus causing clutch shaft 23 torotate at the same speed as shaft 25. It should be understood thatpartial gear tooth engagement at 32 must exist while tooth 33 is slidingaround the face of gear 17. But as soon as tooth 33 drops into the notch34 the teeth 32 will have disengaged. The action, necessarily, isinstantaneous, in other words, the shift from engagement at 32 toengagement at 33-34 must be instantaneous. This shifting will take placein a half second or less, as the relative motion between slidable clutchplate 25 and first clutch plate 17 is 2 revolutions per second, whichmeans that tooth 33 passes notch 34 every half second.

Tooth 33 is located on slidable clutch plate 25 such that when itengages notch 34, the center of coupling 49 is at position a, as shownin Figure 3 of the drawings, and therefore whenever shaft 15 and clutchshaft 23 are rotating at the same speeds, the antenna feed horn 47 willnutate in a conical pattern.

It can thus be seen that the device heretofore described permits anantenna feed horn to be changed from spiral scanning to conical scanningand back again to spiral scanning, when desired, in a relative shortperiod of time.

Obviously many modifications and variations of the present invention arepossible in the light of the above teachings. It is therefore to beunderstood that the in- 4 veution may be practiced otherwise than asspecifically described.

What is claimed is:

1. An antenna drive comprising a shaft, a carrier plate attached to saidshaft, an eccentric shaft attached to said carrier plate, a secondarygear rotatably journaled on said eccentric shaft, a primary gear in meshwith said secondary gear and rotatably mounted to said carrier plate,

means for driving said carrier plate at a fixed speed, first and secondgear trains for selectively driving said primary gear at differentspeeds, one of which is the same as the speed said carrier plate isdrivable, clutch means for selectively connecting one of said geartrains in driving relation with said primary gear, and a gimballymounted antenna feed horn pivotally connected in eccentric relation tothe axis of said secondary gear for vertical movement with respectthereto whereby said antenna feed horn is selectively nutated in spiraland conical patterns.

2. An antenna drive as set forth in claim 1 wherein said clutching meansfor selectively connecting one of said gear trains in driving relationwith said primary gear includes a clutch shaft, first and second clutchplates rotatably mounted on said shaft, a slidable clutch plate slidablyattached to said clutch shaft, and means 'for selectively engaging saidslidable clutch plate with said first and second clutch plates.

3. An antenna drive as set forth in claim 2 wherein said first clutchplate has a single notch on the face thereof and said slidable clutchplate has a single tooth on the face thereof adaptable for engaging saidnotch whereby the engagement of said single tooth in said notch adaptssaid antenna feed horn to be nutated in a conical pattern.

4. An antenna drive comprising a shaft, a carrier plate attached to saidshaft, a secondary gear rotatably journaled to said carrier plate, aprimary gear in mesh with said secondary gear and rotatably mounted tosaid carrier plate, a sleeve rotatably carried by said shaft and indriving relation with said primary gear, a drive motor adaptable fordriving said shaft at a fixed speed, a plurality of gear trains gearedto said drive motor for selectively driving said sleeve at differentspeeds, one of which is the same as the speed said shaft is drivable,clutching means for selectively engaging said plurality of gear trains,solenoid means for operating said clutching means, and a gim- 'ballymounted antenna feed horn pivotally connected at one end thereof ineccentric relation to said secondary gear whereby said antenna feed hornis selectively nutated in spiral and conical patterns.

5. An antenna drive as set forth in claim 4 wherein said clutching meansfor selectively engaging said plurality of gear trains includes a clutchshaft, first and second clutch plates rotatably mounted on said clutchshaft, said first clutch plate having a notch on the face thereof, and aslidable clutch plate slidably attached to said clutch i. shaft andhaving a single tooth adaptable for engaging said notch, whereby theengagement of said single tooth in said notch adapts said antenna feedhorn to be nutated in a conical pattern, and whereby engagement of saidslidable clutch plate with said second clutch plate adapts said antennafeed horn to be nutated in a spiral pattern.

References Cited in the file of this patent UNITED STATES PATENTS

